This was changed in simplepie#745
but without any rationale. The only HTML file is in tests and that should not be manually edited at all.

There are only two markdown files and both use 2 spaces.

Ran the following within `nix-shell -I 'nixpkgs=channel:nixos-unstable' -p zola`
to create the website tree:

    zola init docs

Filled in the website URL and disabled everything for now.

Then created templates based on the successive commits.

Wiki was omitted because it was too big and too outdated.